I. Field of the Invention
The present invention relates to evaluating the efficacy of sterilization processes. More specifically, the present invention provides a useful tool for evaluating whether a sterilization process effectively deactivates biological contaminants within a load to be sterilized, including contaminants residing within the most difficult-to-sterilize locations of the load.
II. Related Art
Various sterilization processes have been employed to eliminate biological contaminants from a load. Such a load, for example, may comprise one or more medical or dental instruments or supplies. Some of these sterilization processes involve the use of a sterilant chemical chosen because it will destroy bacteria and other biological contaminants on the surface of a load if delivered to the surface at an appropriate concentration and for an appropriate period of time. One commonly used sterilant chemical is hydrogen peroxide. When the load has interior exposed surfaces, sterilization will only be successful if the entirety of all interior exposed surfaces is brought into contact with the sterilant at sufficient concentrations and for a sufficient period of time to destroy all biological contaminants present on such surfaces. Biological contaminants not eradicated from medical or dental instruments or supplies prior to use can be transferred to a patient leading to infection.
Much research has been undertaken to develop effective chemical-based sterilization processes. Various test packs have also been developed to attempt to test the efficacy of such processes. These test packs typically provide various paths from the exterior of the test pack to an interior chamber where one or more indicators are located. These indicators often include a chemical indicator which changes color when exposed to the sterilant. These indicators also often include a biological indicator housing organisms which are deactivated if sterilant of a sufficient concentration reaches the biological indicator over a sufficient period of time. Such devices are sometimes referred to as “process challenge devices” because they are intended to present a defined challenge for test purposes comparable to the challenge presented by the most difficult item to be sterilized in a load to be sterilized.
Existing process challenge devices suffer from a variety of problems leading to inaccurate test results. Some problems result from blockage of the aforementioned paths. Such blockage can occur as a result of condensation occluding the path between the interior and exterior of the device. Such blockages can also be the result of pressure changes in the sterilization chamber related to the process being tested causing the walls surrounding the path to collapse. Other problems arise if the challenge presented is either more or less difficult than required given the attributes of the contents of a load to be sterilized. Still other problems arise as a result of the number and spacing of access points into the path from the exterior of the test pack. When multiple access points are present, controlling the degree of challenge is made more difficult and obtaining repeatable test results becomes problematic. Existing process challenge devices are also often difficult or expensive to manufacture. The present invention overcomes these and other problems.